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1.
With the flexibility-based fiber model,the seismic behaviors of RC structures with specially shaped columns,designed according to the current code,are analyzed under unidirectional rare earthquakes using nonlinear dynamic analysis method.The beam strength is calculated with or without consideration of the diaphragm and its reinforcement.The results are compared and the conclusion has been drawn that the bending capacity of beams would be increased due to the effect of diaphragm and its reinforcement,and which would change the failure mechanism of RC frames under rare earthquake,especially in high intensity areas.Therefore the influence of the diaphragm should be considered during the seismic design of the type of structure.  相似文献   

2.
A nonlinear finite element analysis using ANSYS is applied to the vertical mechanical behaviors of three specimens of reinforced concrete transferring joints with inchned columns, which are used in high - rise buildings. A comparison is made between the analytical achievements and the test results, including the mechanical behaviors, load - transferring path and the failure modes, and a good agreement is obtained. The reliability of the software ANSYS in the nonlinear analysis of such reinforced concrete structures is verified and developed.  相似文献   

3.
以竖向荷载和水平地震作用组合下的钢筋混凝土柱和钢柱为对象,研究了失效方程中荷载相关特性对柱承载力抗震可靠性的影响。根据现行《混凝土结构设计规范》和《钢结构设计规范》分析了不同柱弯矩轴力相关曲线的特性。结合多个框架结构实例,对比了柱失效方程中荷载相关曲线与规范考虑情形的异同。实例分析表明:水平地震和竖向荷载组合作用下,小偏压RC柱和工字型钢柱的荷载相关曲线与规范考虑的情形较为符合,均近似为负相关的直线;水平地震和竖向荷载组合作用下,大偏压RC柱的荷载相关曲线则与规范考虑的情形有较大出入,存在明显的正相关段部分。在此基础上,考虑失效方程复杂特性,依据已有的荷载和抗力变量概率模型,采用Monte Carlo法分析了水平地震和竖向荷载组合作用下柱的可靠性。结果表明:钢柱和小偏压RC柱的承载力抗震可靠度随轴压力荷载效应比值的变化幅度较小,与规范模式计算结果较接近;大偏压RC柱的承载力抗震可靠度随轴压力荷载效应比值的变化会有较大幅度波动,与规范模式计算结果差异较大;当轴压力荷载效应比值为负时,大偏压RC柱的承载力抗震可靠度会低于规范计算值较多,现行柱可靠性设计方法会偏于不安全。  相似文献   

4.
In order to investigate the effective seismic capacity design measures of shear wall and to realize expected failure modes under strong earthquake,the existing problems in current seismic capacity design measures are pointed out through theoretical analysis.The effectiveness of the measures of Chinese seismic design code is verified by fine finite element dynamic time-history analysis of examples.Improving measures are then put forward and are verified through example analysis.It is shown the bending ductile demand of bottom section of shear wall increases too much based on moment capacity design measures of Chinese seismic design code 2001 in the rigid foundation assumption under rare earthquake action,and its bearing capacity for vertical axis force loses;the shear capacity design measures of current seismic design code would lead to shear failure in the stores above the bottom ductility strengthening area.Some improved bending and shear seismic capacity design measures of shear wall are proposed and are verified to be effective.  相似文献   

5.
According to the code and technical regulation,an irregular RC frame with specially shaped columns has been designed,which situated at the area of fortification intensity 8. Subsequently,the nonlinear dynamic analysis has been carried out for the structure by inputting ground motions in two directions. After summing up the calculation results,this paper has examined seismic performance of the structure under the rare seismic actions and given a primary evaluation on the structure to see if it could achieve the predetermined anti-seismic aims. It indicates that the structure designed according to the codes can achieve the predetermined anti-seismic aim under the rare earthquake.  相似文献   

6.
Based on dynamic time history analysis, dynamic response behavior of an un supported tunnel through fault zone which was simulated by interface and solid elements was studied under uniform input earthquake wave excitation. The analyses of response behaviors, including displacement difference, acceleration magnification, and plastic zones and so on, were carried out when earthquake wave excitation was input along transverse, longitudinal and vertical of tunnel respectively. The results show that simulation method for fault zone is effective; the earthquake causes obvious displacement difference at fault zone and surrounding rock contacting part. The maximal displacement difference reaches to 51.8mm under transverse uniform input earthquake wave excitation. And the displacement difference under vertical and longitudinal is only 44.3% and 23.1% of the transverse value, respectively; the acceleration magnification in fault zone is significantly greater than that in surrounding rock. Shear failure zone appears at the fault zone and surrounding rock contacting part, and it is especially prominent under input longitudinal earthquake wave excitation. It is proposed that fault zone has significantly influence on the dynamic performance of tunnel. The fault zone and the transitional zones are the control zones of seismic design when tunnel passes through fault zone, thus, the study on the anti seismic measures should be further strengthened.  相似文献   

7.
In this paper,four models are selected as the representatives and applied to nonlinear dynamic analysis program for space frames which is based on the beam-column elements using the finite element flexibility method and the fiber model.Park's test on combined axial and bending columns under cyclic loading are taken as the calibrations,comparisons to material and structural member level are drawn and the analytical results of various models are discussed.  相似文献   

8.
A fiber beam-column element in conjunction with zero-length elements attached to its ends was proposed to simulate the flexural and shear mechanism respectively. Based on the Limit State Material model and the Shear Limit Curve model provided by OpenSees, the nonlinear shear effect of reinforced concrete column and its coupling with the flexural effect were defined. The reliability of the proposed model was validated by means of comparisons with existing test results. Finally, a plane frame from in-situ pushover test was simulated. It is shown that the proposed method, by taking the nonlinear shear effect into account, produces satisfactory results for frame columns with shear strength and stiffness degradation, while the conventional fiber beam-column element can hardly simulate actual flexure-shear failure mechanism for columns characterized by insufficient transverse reinforcement. The proposed method is applicable for nonlinear analysis of reinforced concrete frame structures with shear deficiencies.  相似文献   

9.
The aim is to evaluate the seismic properties of ancient timber structure after strengthening and analyze the failure process and corresponding failure state. Based on the hysteretic behavior and energy dissipation principle of the dovetail column-frame strengthened with CFRP and Arches Brackets under the low reversed cyclic loading, the “potential of destruction-resisting” of the two energy-consuming components is obtained. The dissipated energy of each energy-consuming component under the various earthquake conditions is calculated combining with the shaking table test of ancient timber structure. The model of seismic damage evaluation of the two energy-consuming components is established on the basis of the “potential of destruction-resisting” and the dissipated energy. By means of the energy distribution coefficient, the relationship of the failure state between energy-consuming components and overall strengthened structure is discovered, and the model of seismic damage evaluation of the overall structure under the various earthquake conditions is presented. With the derived model of seismic damage evaluation, the failure coefficient of the energy-consuming components and the overall strengthened structure is quantitatively calculated. According to the failure state, the corresponding damage grade of overall strengthened structure is obtained. The results can provide a reliable theoretical basis for predicting the destruction before earthquake and re-reinforcement to the strengthened ancient timber structures after earthquake.  相似文献   

10.
The mechnical characteristics of concrete is sensitive to the strain rate and it is crucial to consider the effect of load rates on the behavior of reinforced concrete (RC) structures subjected to dynamic loads such as severe earthquakes. In this study, numerical simulations on the dynamic behavior of typical RC column specimens under dynamic loadings with different load rates were performed. Concrete constitutive model considering the strain rate effects proposed by the CEB code was employed with a fiber model to characterize the nonlinear strain rate dependent behavior of RC columns. The developed dynamic fiber element model was validated by comparing the simulated results of four RC column specimens with the fast loading test results. Results show that the developed fiber element model can predict the behavior of RC columns with acceptable accuracy. After valiating the proposed fiber elemen model considering the strain rate effect, the load carrying capacity of different RC columns with various longitudinal reinforcement ratios and volumetric stirrup ratios were simulated. Results show that the trends of the influences of longitudinal reinforcement ratios and volumetric stirrup ratios on the load carrying capacity of the RC columns under dynamic loadings are different.  相似文献   

11.
The stability behavior of shuttle-shaped steel lattice columns subject to combined axial force and bending moment was examined through elastic buckling analysis and geometrically and materially nonlinear analysis. Firstly, the concept of section stiffness variation ratio is proposed for shuttle-shaped lattice columns and the elastic buckling behavior is discussed. Then, the effect of bending moment on the stability behavior of lattice columns is investigated, with the emphasis on the development of axial stress, bending stress and shear stress. The influence of column component spacing and diaphragm thickness on the stability bearing capacity is also analyzed. It is shown that the elastic buckling mode of the lattice column is dependent on its section stiffness variation ratio; for lattice columns with C-shaped buckling mode, the reduction in stability bearing capacity caused by bending moment is smaller than that of columns with S-shaped buckling mode; the maximum stability bearing capacity of the lattice column can be achieved by adjusting the column component spacing, and the spacing corresponding to the maximum capacity is basically consistent with the critical spacing for transformation of C-shaped buckling mode and S-shaped mode; and it is more effective to increase the thickness of columns with S-shaped buckling mode to get larger bearing capacity.  相似文献   

12.
With examples of three 6-storey RC frames by using an elasto-plastic dynamic analysis program PL-AFJD of plane frame, developed by the second author of this paper, the frames designed for different earthquake-intensity regions (intensity category 7, 8, 9 respectively) are analyzed nonlinearly under four ground motions at the action of rare earthquake. Three frames strictly conform to the National Standard GBJ10-89 and the dimensions of columns are changed once along the height. The structure designed on intensity category 7 shows a relatively small response, which could be sustained by the structure. Though the hinge formation in columns can not be prevented, the inelastic deformation of columns is not serious, the structure at intensity category 9 exhibits a relative strong response, but the deformation of most columns is within the capacity and the trend to form a soft-storey does not appear. It is the structure at intensity category 8 that shows a severe response. Though the visible soft-storey can not be found, the deformation of some columns is beyond the capacity of inelastic hysteretic deformation under certain inputs, which indicate the possibility of local collapse.The elementary analysis results demonstrate the different effectiveness of seismic provisions for three different earthquake-intensity regions, which may be a reference to the amendment of National Design Standard.  相似文献   

13.
It provides several typical mega plane frame designs on condition that the variables are the combination of varying amplification factors of moment at bottom sections of ground floor columns of the minor frame on the major beams. The elastic-plastic dynamic analysis program Drain-2d+ of the plane structure is used to get elastic-plastic time-history analysis for each typical mega frame under the action of seism. The autuors obtain the information of the mechanical transmutation characteristics, the emergency of the plastic hinge and the weak point of the whole structure under the action of seism, from which the correct thinking of how to obtain the design value of amplification factors of moments at bottom sections of ground floor columns of the minor frame on the major beams is found. The reasonable design values are recommended in order to provide some suggestions for the design of the reinforced concrete mega-frame structure.  相似文献   

14.
In this paper,a computer program for nonlinear analysis ofa special frame is developed.The frame has all columns fixed at the base and hinged at the top.By taking the frame as a whole,the behavior ofthe frame is studied from the test results of three specimens of the frame andlarge amount of results of computer program.The minimun value of total sumof vertical loads sustained by the frame is found and a new method of deter-mining the effective length of stepped columns is suggested.  相似文献   

15.
Seismic responses of power transmission tower-line system under multi-component excitations were analyzed by numerical simulation. A three-dimensional finite element model of transmission tower-line coupled system considering the geometric nonlinearity of transmission line was established. Twelve seismic records of different soil types were selected based on Code for Design of Seismic of Electrical Installations. Seismic responses of power transmission tower-line system under single component, two horizontal component and multi-component excitations were investigated using nonlinear time history analysis method, respectively. The results show that the responses of transmission tower-line system under multi-component excitations are significantly larger than those under single component excitation only, especially for considering vertical ground motion excitation only, and neglecting multiple nature of ground motion in analysis will underestimate the responses of the structure. To obtain an accurate seismic response and a better seismic design of transmission tower-line system, multi-component ground motion inputs need to be considered. The results provide reference for seismic design of transmission line practical engineering.  相似文献   

16.
Joints are the most important parts of the space structure, the load-derormation curve (hysteretic curve) under repeated loading is the comprehensive reflection of their mechanical properties such as ductility, energy dissipation capacity, strength, stiffness and so on. By the simulation experiment analysis and the finite element simulation between the two models of hidden welding and no-welding hidden in K-type node in the chord axial reciprocating load resulted in the failure modes and hysteretic curve, the result of comparative analysis about finite elements is consistent with that of experiment study. The results show that the destroyment at hidden welding seam node is partly, the take-over is broken down at the welds finally. The welding line is destroyed overall when facing the destroyment of no-welding node. The carrying capacity of the hidden welding is obvious. Through the finite element simulation analysis instead of phase through node hysteretic performance test is feasible.  相似文献   

17.
A novel double ring plate gear reducer (DRPGR) is designed and its experimental validation is conducted. By using the closed graph method, the modification coefficients of internal gearing in DRPGR are determined. Based on this, the overall structure of the reducer is designed and its kinematics simulation is achieved. With APDL programming language of ANSYS, a 3D finite element (FE) model of DRPGR is established, and its modal analysis and loaded tooth contact analysis (LTCA) are conducted respectively. The modal analysis reveals that the lower natural frequencies of DRPGR are much higher than the input frequency and the lower modes can be classified as vertical and horizontal bending of input and output shafts. The LTCA indicates that three pairs of gear teeth contact simultaneously at rated output torque. Due to the multi teeth contacts, the maximum stress is much lower than the permissible stress of internal gearings. The experimental tests of the prototype validate that DRPGR is adapted to both single driven and dual driven work condition. When single droved, DRPGR can eliminate the kinematic uncertainty by non 180 degree phase difference design. DRPGR claims a better dynamic performance in dual driven work condition. The efficiency of DRPGR increases with the increment of output torque and the reducer has an excellent short term overloaded capacity. The experimental results validate that the proposed method can be used to guide the design of that kind of reducer.  相似文献   

18.
Three models of 3D cast-in-place RC frame structures are simulated in ABAQUS. In the three models, one represents the actual RC frame structure with monolithic slab, one represents the open frame structure used in structural design currently, which means truss structure at the stage of calculating internal forces of frame beams and columns, and the third one represents the open frame structure which takes into account some slab reinforcement in the rectangle section of frame beam to consider the slab participation in the flexural capacity of frame beam. By investigating the failure mode of these three models, the development of plastic hinges, the reinforcement stress of beam, column and slab in the models, the influence of monolithic slab to the bending resistance of beam end is studied. It shows that the existence of slab makes the failure mode of actual RC frame structure different from the design criteria of strong column weak beam. It also indicates that the slab participation in the bending resistance of beam end is not only expressed in the slab reinforcement but also in the structure integral performance. Besides, when using the effective flange width to consider the slab reinforcement participation, the structure integral performance, lateral displacement and other relevant factors should be taken into account.  相似文献   

19.
基于回归分析的苏州古典园林庭园空间构成   总被引：2，自引：1，他引：1  
陈莺 《中国农学通报》2013,29(19):203-209
苏州古典园林历史悠久,集中国园林之精髓。以苏州宅园最具代表性,保存完整的13个古典园林作为研究对象。基于空间构成的基本原理,提出庭园空间是构成园林的基本空间单元,深入剖析庭园空间的构成规律,提取庭园空间的构成要素,借助SPSS 18.0分析软件,利用有序回归分析方法对量化后的庭园空间水平、垂直的构成要素进行分析。研究结果可总结出：苏州古典园林的庭园数量规律;庭园水平、垂直构成要素及相互间的配置关系;庭园的开敞与封闭特点。希望该项研究能为园林今后的设计与建设提供有价值的参考。  相似文献   

20.
The accurate calculation of the deformation capacity of structures is very important to performance-based seismic design, which satisfies the explicit deformation demands. The method to evaluate drift capacity of fiber reinforced polymer (FRP) confined reinforced concrete circular columns under simulated seismic loading is focused. Firstly, the moment-curvature relationship of FRP confined sections of reinforced concrete (RC) circular columns is simulated by numerical analysis. It is found that the calculated ultimate curvature is significantly less than the test result, and the difference is controlled by the axial load ratio of the tested columns. According to the numerical and the test results, an equation is proposed to modify the calculated ultimate curvature. Based on this, the drift capacity can be predicted with the equivalent plastic hinge method. The calculated result agrees well with the test result when FRP amount is low, but it is significantly larger when FRP amount increases. Finally, the main parameters exerting influences on the drift capacity of the FRP-confined RC circular column are analyzed.  相似文献   

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